gh-117404: Add structured version info for compression modules by serhiy-storchaka · Pull Request #150567 · python/cpython

serhiy-storchaka · 2026-05-29T07:23:23Z

Add a number of constants in modules zlib, bz2, lzma, and compression.zstd, which provide information about the version of libraries that were used for building the module and that are actually loaded:

zlib.zlib_version -- an alias of zlib.ZLIB_RUNTIME_VERSION
zlib.ZLIB_VERSION_INFO
zlib.zlib_version_info
~~zlib.zlibng_version~~
zlib.ZLIBNG_VERSION_INFO
~~zlib.zlibng_version_info~~
bz2.bzlib_version
bz2.bzlib_version_info
lzma.LZMA_VERSION
lzma.lzma_version
lzma.LZMA_VERSION_INFO
lzma.lzma_version_info
compression.zstd.ZSTD_VERSION
compression.zstd.ZSTD_VERSION_INFO

Make compression.zstd.zstd_version_info a named tuple.

Issue: Add structured version info for compression modules #117404

read-the-docs-community · 2026-05-29T07:28:18Z

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library/asyncio-policy.html

Add a number of constants in modules zlib, bz2, lzma, and compression.zstd, which provide information about the version of libraries that were used for building the module and that are actually loaded: * zlib.zlib_version -- an alias of zlib.ZLIB_RUNTIME_VERSION * zlib.ZLIB_VERSION_INFO * zlib.zlib_version_info * zlib.zlibng_version * zlib.ZLIBNG_VERSION_INFO * zlib.zlibng_version_info * bz2.bzlib_version * bz2.bzlib_version_info * lzma.LZMA_VERSION * lzma.lzma_version * lzma.LZMA_VERSION_INFO * lzma.lzma_version_info * compression.zstd.ZSTD_VERSION * compression.zstd.ZSTD_VERSION_INFO Make compression.zstd.zstd_version_info a named tuple.

serhiy-storchaka · 2026-07-01T17:51:08Z

@emmatyping, could you please look at this PR?

…-versions-2 # Conflicts: # Doc/whatsnew/3.16.rst

serhiy-storchaka · 2026-07-24T10:45:04Z

@gpshead, could you please review this PR? It implements the naming scheme we converged on in gh-117404 (*_version for the string version, *_version_info for a named tuple, ALLCAPS for the compile-time version).

emmatyping · 2026-07-25T03:50:11Z

Sorry for not reviewing sooner, will try to get to this tomorrow

…-versions-2 # Conflicts: # Doc/whatsnew/3.16.rst

StanFromIreland · 2026-08-22T11:21:03Z

   The version string of the zlib library actually loaded by the interpreter.

   .. versionadded:: 3.3
+   .. versionchanged:: next


I think we should soft-deprecate the old one, otherwise we're inconsistent.

Maybe later, when the new name became widespread.

StanFromIreland · 2026-08-22T11:21:22Z

+        self.assertGreaterEqual(v.minor, 0)
+        self.assertGreaterEqual(v.patch, 0)
+
+        self.assertEqual(bz2.bzlib_version.split(',')[0], '%d.%d.%d' % v)


If I build with --with-bzip2=bzip2-rs:

test test_bz2 failed -- Traceback (most recent call last): File "/home/stan/dev/cpython/Lib/test/test_bz2.py", line 1247, in test_bzlib_version self.assertEqual(bz2.bzlib_version.split(',')[0], '%d.%d.%d' % v) ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ AssertionError: '1.1.0-libbz2-rs-sys-0.2.5' != '1.1.0' - 1.1.0-libbz2-rs-sys-0.2.5 + 1.1.0

StanFromIreland · 2026-08-22T11:21:46Z

+    {0}
+};
+
+static PyStructSequence_Desc zlib_version_desc = {


This was all copy pasted but not updated for bz2.

StanFromIreland · 2026-08-22T11:22:38Z

+    int pos = 0;
+    unsigned int major = 0, minor = 0, revision = 0, subversion = 0;
+
+    sscanf(string, "%u.%u.%u.%u", &major, &minor, &revision, &subversion);


sscanf can fail?

Yes, it can. Then we will get zeros for missing components. I think it is better than a hard error.

I suggest a comment, to avoid people agents trying to fix this in the future.

serhiy-storchaka · 2026-08-22T12:42:21Z

   The version string of the zlib library actually loaded by the interpreter.

   .. versionadded:: 3.3
+   .. versionchanged:: next


Maybe later, when the new name became widespread.

serhiy-storchaka · 2026-08-22T12:50:54Z

+    int pos = 0;
+    unsigned int major = 0, minor = 0, revision = 0, subversion = 0;
+
+    sscanf(string, "%u.%u.%u.%u", &major, &minor, &revision, &subversion);


Yes, it can. Then we will get zeros for missing components. I think it is better than a hard error.

Co-authored-by: Stan Ulbrych <stan@python.org> Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>

* Register collect_bz2() and collect_lzma() in pythoninfo's collect_info(). * Do not assume a particular suffix of bz2.bzlib_version: libbz2-rs reports "1.1.0-libbz2-rs-sys-0.2.5" where bzip2 reports "1.0.8, 13-Jul-2019". * Document ZLIB_RUNTIME_VERSION and zlib_version as a single entry and tell in which version each of them was added. * Tell which fields the runtime *_version_info named tuples have by referring to their compile-time counterparts. * Remove a line duplicated when applying a suggestion for ZLIB_VERSION_INFO. * Fix indentation, alignment and line lengths of the added code. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

serhiy-storchaka · 2026-08-22T13:24:24Z

Thank you for your review @StanFromIreland. I addressed your comments.

StanFromIreland

Few little nits, but otherwise I like the API.

StanFromIreland · 2026-08-22T17:34:40Z

+Miscellaneous
+-------------
+
+Information about the version of the bzip2 compression library in use


Maybe clarify what "in use" means, as in other places we distinguish compile/run time.

It repeats existing phrase from zlib.rst. What is your suggestion?

For zlib, we have both runtime and compile time constants, whereas here we only have runtime. It's not clear in the documentation if bzlib_version is runtime or compile time information. So, I suggest either clarifying here, or below in their documentation (but that's a little duplicative).

StanFromIreland · 2026-08-22T17:34:52Z

+};
+
+static PyStructSequence_Desc zstd_version_desc = {
+    "_zstd.zstd_version_info",   /* name */


Hmm, this will leak into the repr now, right? We could do like we have elsewhere:

cpython/Modules/posixmodule.c

Lines 2504 to 2505 in 999a046

static PyStructSequence_Desc stat_result_desc = {

"os.stat_result", /* name; see issue gh-63408 */

Unlike os.stat_result, the name of this type is not public. It cannot be used, because it conflicts with the name of the instance (like in sys.version_info and other precedences).

Interesting, Claude had the same complaint, but I convinced it.

StanFromIreland · 2026-08-22T17:34:59Z

 };

+
+PyDoc_STRVAR(bzlib_version__doc__,


Suggested change

PyDoc_STRVAR(bzlib_version__doc__,

PyDoc_STRVAR(bzlib_version_info__doc__,

Oh, this will need a lot of changes.

StanFromIreland · 2026-08-22T17:35:06Z

+};
+
+static PyObject *
+make_zlibng_version(PyTypeObject *type, const char *string)


This is almost the same as make_zlib_version, it can be refactored.

* Explain in a comment why the result of sscanf() is not checked. * Merge make_zlib_version() and make_zlibng_version() into a single make_version_info(). * Rename the static names for the *_version_info named tuples, so that they match the name of the type. * Tell in the bz2 docs that bzlib_version and bzlib_version_info are the version of the library loaded at runtime, and that the version used for building the module is not available. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

serhiy-storchaka requested review from AA-Turner and emmatyping as code owners May 29, 2026 07:23

bedevere-app Bot mentioned this pull request May 29, 2026

Add structured version info for compression modules #117404

Open

bedevere-app Bot added the awaiting core review label May 29, 2026

serhiy-storchaka force-pushed the compression-library-versions-2 branch from f57fc45 to 76354de Compare May 29, 2026 07:39

serhiy-storchaka added 2 commits May 29, 2026 12:33

Remove runtime zlib-ng versions which are not available in compat mode.

1175471

Fix test_zlibng_version.

0c71967

StanFromIreland reviewed Jun 2, 2026

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Comment thread Doc/library/compression.zstd.rst

serhiy-storchaka added 2 commits June 7, 2026 18:27

Merge branch 'main' into compression-library-versions-2

a41ea82

Merge branch 'main' into compression-library-versions-2

a6b7099

Merge remote-tracking branch 'upstream/main' into compression-library…

a0aaa31

…-versions-2 # Conflicts: # Doc/whatsnew/3.16.rst

Merge remote-tracking branch 'upstream/main' into compression-library…

cd5aac2

…-versions-2 # Conflicts: # Doc/whatsnew/3.16.rst

StanFromIreland reviewed Aug 22, 2026

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serhiy-storchaka commented Aug 22, 2026

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serhiy-storchaka and others added 2 commits August 22, 2026 15:53

Apply suggestions from code review

6e04c64

Co-authored-by: Stan Ulbrych <stan@python.org> Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>

StanFromIreland reviewed Aug 22, 2026

View reviewed changes

	static PyStructSequence_Desc stat_result_desc = {
	"os.stat_result", /* name; see issue gh-63408 */

	PyDoc_STRVAR(bzlib_version__doc__,
	PyDoc_STRVAR(bzlib_version_info__doc__,

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